Surface piercing concave disc hydrofoil



March 1966 J. A. STURGEON ETAL 3,237,582

SURFACE PIERCING CONCAVE DISC HYDROFOIL Filed June 7, 1965 4Sheets-Sheet INVENTORS c/OSEPH 4. STUPGEOM,

' March 1966 J. A. STURGEON ETAL 3,237,582 I SURFACE PIERCING CONCAVEDISC HYDROFOIL Filed June 7, 1965 4 Sheets-Sheet 2 March 1, 1966 J. A.STURGEON ETAL 3,237,582

SURFACE PIERGING CONCAVE DISC HYDROFOIL INVENTORS S fl/QGEO 4Sheets-Sheet 5 c/OSEPH 4. 0%:77 QW25 E STaPGEOA/ Filed June 7, 1965March 1, 1966 J. A. STURGEON ETAL 3,237,582

SURFACE PIERCING CONCAVE DISC HYDROFOIL Filed June 7, 1965 4Sheets-Sheet 4 IN V EN TORS 4055 J. 57 R950 7/30/1145 5 ra flea UnitedStates Patent 3,237,582 SURFACE PIERCING CONCAVE DISC HY DROFOIL JosephA. Sturgeon and Thomas E. Sturgeon, Seattle, Wash. Filed June 7, 1965,Ser. No. 470,264 4 Claims. (Cl. 11466.5)

This application is a continuation-in-part application of ourapplication Serial No. 300,507, filed August 7, 1963, and now beingabandoned.

The present invention relates to watercraft generally and in particularto a hydrofoil boat having surface piercing concave discs.

-An object of the present invention is to provide a hydrofoil for awatercraft which to a great extent overcomes the problem of skinfriction, one which automatically sheds itself of debris such as grassor seaweed when collected on the leading edge of the hydrofoil, one inwhich the problem of cavitation will be eliminated, and one which ishighly effective in action.

:Another object of the present invention is to provide for a watercrafta hydrofoil assembly consisting of four discs arranged two at theforward end of the craft and two at the aft end of the craft, the discsbeing arranged so as to be tilted toward the craft and also tilted awayfrom the movement of the craft through the water.

.A further object of the present invention is to provide ahydrofoilarrangement which permits a watercraft to travel well in rough water,and one which achieves greater stability of the craft not heretoforepossible with present hydrofoil designs.

.A still further object of the present invention is to provide arotating stabilizer which offers little or no resistance to travelthrough the water but provides stability for the watercraft on which itis installed while making turns or traveling straight.

Yet another object of the present invention is to provide a hydrofoilarrangement which is useful on all types of watercraft, one in whichthere are two or more hydrofoil means each individually suspended andresiliently mounted so as to absorb shock, one which is sturdy inconstruction and of simple structure, and one which is economicallyfeasible.

These and other objects and advantages of the present invention will befully apparent from the following description when taken in connectionwith the annexed drawings, in which:

FIGURE 1 is a side elevational view of a boat with a mid-portion brokenaway, showing the hydrofoil arrangement of the present inventioninstalled thereon, the dotted line showing the raised-out-of-useposition of the vertical stabilizer;

FIGURE 2 is a fragmentary front elevational view of the assembly shownin FIGURE 1;

FIGURE 3 is a view in section and on an enlarged scale of the supportmeans for one of the hydrofoils;

FIGURE 4 is a view similar to FIGURE 2 showing a modified form of theinvention;

FIGURE 5 is a fragmentary side elevational view of the assembly shown inFIGURE 4;

FIGURE 6 is a view on an enlarged scale taken on the line 6-6 of FIGURE5;

FIGURE 7 is a view taken on the line 77 of FIG- URE 2;

FIGURE 8 is a front elevational view of a modified form of theinvention;

FIGURE 9 is a bottom view of a preferred disc embodying a modificationof the invention; and

FIGURE 10 is a front elevational view taken along lines 1010 of FIGURE9.

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Referring in detail to the drawings in which like numerals indicate likeparts throughout the several views, the reference numeral 10 designatesgenerally a boat hull of more or less conventional design for which noinvention is claimed.

Although in FIGURE 1 only two hydrofoil assemblies 12 and 14 are shown,it is to be understood that there are two on each side of the hull 10with the assembly 12 positioned outwardly of and adjacent the forwardend of the hull 10 and the assembly 14 positioned adjacent the aft endof the hull 10.

As the assemblies 12 and 14 are nearly identical, they will be describedwith reference to the assembly 12.

As shown in FIGURE 2, the assembly 12 includes a strut 16 and a shaft 18rotatably mounted in the lower end of the strut 16. The disc 20 of thepresent invention is fixedly secured by welding or other means to thelower end of the shaft 18.

As shown most clearly in FIGURE 3, bearing assemblies 22 and 24 supportthe shaft 18 for rotation relative to the strut 16, the bearingassemblies 22 and 24 being mounted in a housing 26 which is providedwith a pair of trunnions 28 on the lower end thereof for mounting of thestrut 16 on the hull 10 with the support brackets 28 and 30, as shownmost clearly in FIGURE 1.

The upper end of the strut 16 is connected by a nut or bracket assembly32 to the hull 10 for limited upward and downward movement as controlledby a shock absorber assembly 34 interposed between the housing 26 andanother portion of the hull 10.

An important feature of the present invention resides in the fact thatthe disc 20 is concave and has its concave face facing downwardly, asshown most clearly in FIG- URE 7. It is to be understood that the curveshown in FIGURE 7 is not necessarily a limitation on the invention andother shapes of concavity may be employed as desired.

Another feature of the invention resides in the provision of a verticalstabilizer assembly 36 consisting of a rotatable disc 38 mounted on astub shaft 40, the stub shaft 40 being suspended from a yoke 42pivotally connected to the underside of the hull 10, as shown in FIGURE2.

The hull 10 is provided with a well, indicated by dotted lines at 44,into which the disc 38 may be moved from the full line position shown inFIGURE 1 to the dotted line position shown in FIGURE 1.

With reference to the modified form of the invention shown in FIGURE 4,the assembly 12 includes the disc 20 and a vertical stabilizer disc 38'carried on one end of a strut 46. The strut 46 projects horizontallyfrom the lower end of the strut housing 48 which is mounted for limitedresilient movement upward and downwardly, as described above withreference to the assembly 12.

The disc 20 is rotatably mounted on the strut housing 48 for freerotation about the strut housing 48 as an axis.

In FIGURE 8, a modified form of the invention is shown in which the disc20 is rotatably mounted on the lower end of a shaft 50 which has itsupper end portion telescopingly mounted within oleo strut assembly 52which provides a resilient mount for the disc 20,

As shown most clearly in FIGURES 1 and 2, each disc 20 is disposed at alateral angle with respect to the hull 10 and also at a fore and aftangle with respect to the path of movement of the hull 10 through thewater.

The amount of this angle is such that a portion of the peripheryadjacent the forward end of the boat of each disc 20 is out of thewater, as shown in FIGURE 1. Traveling movement of the hull 10 throughthe water by a conventional drive means (not shown) causes each disc 20to rotate and to thereby lessen the friction of the disc in the water.

The same applies to the vertically disposed disc 38 which serves as astabilizer and, as shown in FIGURE 1, only a portion of the discperiphery is emersed in the water so that it too will be caused torotate by the friction of the discs passing through the water.

It' is.to beunderstood that the invention is not to be limited by theangle of the discs, size of the discs, or its relative position to thehull as illustrated in the accompanying drawings. Nor is the shape ofthe concave face of the discs to be limited to that illustrated.

It will be seen therefore that the rotating disc 20 and the rotatingdisc 38. will be free of any debris-catching characteristics because ofthe rotation of the disc in the water..

Theiprovision of the resilient mounting of each of the discs providesfor absorption of shock transmitted through rough water or for otherreasons.

InFIGURES 9 and 10 there is shown a modified or alternative. andpreferred embodiment of the disc that is capable of being used in thepresent invention. The disc 70' is adapted to be. rotatably mounted froma rotatable shaft 82 in which the upperend thereof is telescopicallymounted, as shown in FIGURE 8, for rotation. The disc 70' is.of circularconfiguration, as shown in FIGURE 9, but thecrossasectional;configuration thereof is shown so that it is. evidentthe cross-sectional curvature changes substantially'rapidly as itapproaches the peripheral portion, asshown as curve 84. The intermediateportion of theinner face of: the disc 70 is'a curve generally shown as86, and is substantially linear in cross-section to provide thegenerally, planar section formed by the surface of revolution of thecurve 86. It is foundthat the construction of the disc. 70 provides theoptimum characteristics in supporting anddriving a hydrofoil by means ofthe concave construction that is exemplified in FIGURES 9 and 10.

The fore and' aft angle of shaft 82. with respect to the path ofmovement of the hull through the water is generally that oftheembodiments shown in FIGURES 1-8.

Although the invention is not to be limited by the angles-or the.configuration of the concave disc, it is to be understoodthat theconcavity described and shown in the illustration .of the invention inFIGURES 9 and 10 is intended to show. what has been found to be theultimate and. optimum characteristics of the preferredand best modeiofthe invention.

Additional embodimentsof the invention in this specification will occurto others and therefore it is intended that the scope of the inventionbe limited only by the appended claims and not by the embodimentsdescribed hereinabove. Accordingly, reference should be made to thefollowing claims in determining the full scope of the invention.

What is claimed is:

1. In at least a watercraft having a hull, a pair of downwardly andoutwardly extending struts secured to said hull with one strut on eachside thereof, a shaft freely rotatively journaled in each strut andextending downwardly therefrom in diverging relation to the hull, a discmounted on the lower end of each shaft, each disc having a concave lowersurface with the axis of rotation thereof converging upwardly andrearwardly in relation to the boat hull and also inwardly toward thecenterthereof, whereby the wetted surfaces of the disc will moveinrotation with the flow of water reducing skinfriction.

2. In at least a watercrafthaving a hull, a pair=of=downwardly andoutwardly extending struts secured tosaid hull with one strut oneach'side thereof, a shaft freely rotatively journaled in each strut andextendingdowmwardly therefrom in diverging relation tothe hull," a-

concave disc mounted'on the lowerend of each'shaft, the concavity of thedisc being of such a radiusiofcurvature that the concavity increasesattheper-ipheral portions of the disc, and ismore generally planarat'theintermedi ate and central portions-of the disc, whereby the wettedsurfaces of the disc will move in rotation with'the flow of waterreducing skin friction and providing improved support and operation ofthe hydrofoil.

3. The invention according to claim 1 wherein the concavity of the lowersurface of the disc is generally planar throughout the central andintermediate portions of the disc, and is sharply contoured towardthe-peripheral; portions thereof.

4. The invention according to claim 1 wherein the intermediate andcentral lower surface of the concave-disc is generally planar throughoutthese'portionsb No references cited.

MILTON BUCHLER, Primary-Examiner.

ANDREW H FARRELL, Examiner.

1. IN AT LEAST A WATERCRAFT HAVING A HULL, A PAIR OF DOWNWARDLY ANDOUTWARDLY EXTENDING STRUTS SECURED TO SAID HULL WITH ONE STRUT ON EACHSIDE THEREOF, A SHAFT FREELY ROTATIVELY JOURNALED IN EACH STRUT ANDEXTENDING DOWNWARDLY THEREFROM IN DIVERGING RELATION TO THE HULL, A DISCMOUNTED ON THE LOWER END OF EACH SHAFT, EACH DISC HAVING A CONCAVE LOWERSURFACE WITH THE AXIS OF ROTATION THEREOF CONVERGING UPWARDLY ANDREARWARDLY IN RELATION TO THE BOAT HULL AND ALSO INWARDLY TOWARD THECENTER THEREOF, WHEREBY THE WETTED SURFACES OF THE DISC WILL MOVE INROTATION WITH THE FLOW OF WATER REDUCING SKIN FRICTION.